One of his most popular articles, cited and critiqued by Jeff McMahan in his own work 'The Ethics of Killing', is called "Killing the Innocent in Self-Defense". In this article, Otsuka develops what he calls the Moral Equivalence Thesis, according to which Innocent Threat (e.g., the body of Falling Person is about to kill you by crushing you to death but who was thrown off the top of a building by an evil Villain) is on a moral par with Bystander, or one who is not at all responsible for whatever endangers your life. Imagine a javelin is heading toward you and will kill you unless you pull Bystander into its path so it kills Bystander instead. Because it would be morally impermissible to kill Bystander in this way, it would also be morally impermissible for you to kill Falling Person by, say, vaporizing him with a ray gun. Further, it is morally impermissible to kill an Innocent Aggressor, or someone who endangers your life because of her intention to kill you but whose actions are beyond her control. Imagine someone who has been hypnotized and whose aim is to kill you. It is wrong to kill Innocent Aggressor because he is on a moral par with Innocent Threat, who is on a par with Bystander. So, it is wrong to kill Innocent Aggressor because he is on a par, morally, with Bystander.